The influence of plasma glucose upon pulsatile ocular blood flow in subjects with Type II diabetes mellitus (original) (raw)
Related papers
Pulsatile ocular blood flow in untreated diabetic retinopathy
Acta Ophthalmologica Scandinavica, 2009
Purpose: To measure the pulsatile component of total ocular blood flow in patients with untreated diabetic retinopathy.Subjects and Methods: An adapted pneumotonometer attached to a slit-lamp biomicroscope. 82 age-matched subjects divided into 4 groups: non-diabetic controls (n = 22); diabetics with no clinical retinopathy (n = 20); background diabetic retinopathy (n = 20); pre-proliferative/proliferative diabetic retinopathy (n = 20).Results: The mean pulsatile ocular blood flow values were found to be increased in all grades of diabetic retinopathy (no retinopathy 818 μl/min, background 1015 μl/min, pre-proliferative/proliferative 1097 μl/min) compared to the control group (644 μl/min). These pulsatile ocular blood flow values were significantly higher (p<0.05) in the background and pre-proliferative/proliferate retinopathy groups compared to controls. Pulse volume and pulse amplitude were also higher in the diabetic subjects. Mean arterial blood pressure did not differ across the groups studied.Conclusion: Pulsatile ocular blood flow was found to be higher in diabetics compared to controls and appears to increase as the severity of retinopathy progresses. Such a hyperdynamic circulation may contribute to the pathogenesis of diabetic eye disease.
Can pulsatile ocular blood flow distinguish between patients with and without diabetic retinopathy?
Clinical and Experimental Optometry, 2007
Our aim was to determine if pulsatile ocular blood flow (POBF) measurements could distinguish between type 2 diabetes mellitus (DM) subjects with and without diabetic retinopathy (DR). Methods: Ninety-eight DM subjects were recruited. POBF was measured using an Ocular Blood Flow tonometer and retinopathy was assessed using retinal digital photography. The duration of diabetes, blood pressure, glycosylated haemoglobin and plasma glucose level were also recorded. Results: Seventy-two subjects had no DR and 26 subjects exhibited mild to moderate non-proliferative DR. POBF was higher in those subjects with non-proliferative DR but did not reach significance. Those subjects receiving insulin treatment had a significantly longer duration of DM, higher HbA1c and plasma glucose levels and greater incidence of non-proliferative DR compared to subjects receiving oral hypoglycaemic agents, who in turn demonstrated higher levels of these parameters than those who were controlled by diet alone (ANOVA p < 0.05 in all cases). POBF was found to increase with level of management but not significantly so. Conclusions: A single measurement of POBF does not distinguish between subjects with and without mild/moderate non-proliferative DR.
Investigative ophthalmology & visual science, 1996
The authors investigated retinal blood flow changes in patients with insulin-dependent diabetes mellitus (IDDM) and no diabetic retinopathy compared to age-matched subjects without diabetes. They also investigated whether blood glucose levels could modulate retinal blood flow in these patients with diabetes and whether this modulation would impact retinal blood flow data used in cross-sectional studies assessing changes in retinal blood flow. Retinal blood flow was measured using video fluorescein angiography, and blood glucose levels were manipulated using glucose clamp methodologies with continuous basal insulin replacement. Blood glucose levels were clamped at 100, 200, and 300 mg/dl. Retinal blood flow measurements were performed at each blood glucose level after subjects had been stabilized for an hour at each of the different blood glucose levels. Retinal blood flow was found to be significantly decreased (P< 0.01) in the group of patients with no diabetic retinopathy (19.4...
Ophthalmology, 1985
To quantify the vascular deterioration of the diabetic retina, retinal circulatory changes in 45 insulin-dependent diabetic patients, and in 17 normal controls, were measured and divided into four groups according to severity of retinopathy. The noninvasive laser Doppler technique was used to measure the systolic/diastolic variation of red blood cell velocity (V) at sites along temporal retinal arteries. Flow pulsatility [V (systole)fV ( diastole)] was 18% lower (P < 0.00001) in the mild-retinopathy group than in normal controls, but 35% higher (P < 0.001) in the severe-retinopathy group than in the mild-retinopathy
Retinal haemodynamics in individuals with well-controlled type 1 diabetes
Diabetologia, 2008
Aims/hypothesis Abnormalities in retinal haemodynamics have been reported in patients with type 1 diabetes in advance of clinical retinopathy. These abnormalities could therefore be useful as early markers or surrogate endpoints for studying the microangiopathy. Since the DCCT, the increased focus on good glycaemic control is changing the natural history of diabetic retinopathy. Based on this, the aim of this study was to investigate whether patients with type 1 diabetes treated entirely or mostly in the post-DCCT era and tested in the absence of confounding factors show retinal haemodynamic abnormalities. Methods We measured retinal haemodynamics by laser Doppler flowmetry in 33 type 1 diabetic individuals with no or minimal retinopathy (age 30±7 years, duration of diabetes 8.8±4.6 years, 9% showing microaneurysms), and 31 age-and sex-matched non-diabetic controls. The study Diabetologia (
Microvascular Research, 2007
The aim was to quantify the magnitude of retinal arteriolar vascular reactivity to a hyperglycemic provocation in diabetic patients stratified by severity of retinopathy and in age-matched controls. The sample comprised 20 non-diabetic controls (Group 1), 19 patients with no clinically visible DR (Group 2), 18 patients with mild-to-moderate non-proliferative DR (Group 3) and 18 patients with diabetic macular edema (Group 4). Retinal hemodynamic measurements using the Canon Laser Blood Flowmeter (CLBF-100) were acquired before and 1 h after drinking a standardized oral glucose load drink. The magnitude of the retinal vascular response, as well as max:min velocity ratio and wall shear rate (WSR), was calculated and compared across groups. A significant change in blood glucose level was observed for all groups (p < 0.05). The change in blood glucose elevation was significantly less in Group 1 compared to the other groups. No significant change in arteriolar diameter, blood velocity, blood flow, max:min velocity ratio and WSR was found in patients with diabetes and in age-matched subjects without diabetes. The results of this study indicate that retinal arteriolar blood flow is unaffected by acute elevation of blood glucose using an oral glucose load drink in patients with diabetes and in agematched controls. This lack of a blood flow response to acute hyperglycemia in patients with early sight-threatening DR may be explained by a loss of retinal vascular reactivity.
Retinal haemodynamics in patients with early diabetes mellitus
British Journal of Ophthalmology, 1996
AimsIBackground-The retinal circulation was investigated in a group of 19 patients with insulin dependent diabetes mellitus with less than 4 years of disease duration and no evidence of diabetic retinopathy. Results ofthese patients were compared with those of 16 age-matched normal controls. Methods-Venous diameter (D) was measured from monochromatic fundus photographs. Maximum erythrocyte
Retinal blood flow during hyperglycemia. A laser Doppler velocimetry study
Investigative Ophthalmology & Visual Science
The effect of different rates of glucose infusion on the retinal circulation was studied in Gottingen breed minipigs. Seven minipigs were made hyperglycemic rapidly with an intravenous bolus injection of 50% dextrose, after which a slow dextrose infusion maintained hyperglycemia for 60 minutes. Seven minipigs were more gradually made hyperglycemic over 60 minutes with a slow intravenous infusion of 50% dextrose, and a further seven had a control infusion of urea of equal volume and osmolality over 60 minutes. Retinal blood flow (RBF) was determined from the maximum (centerline) velocity of the blood (Vmax) (determined by bidirectional laser doppler velocimetry) and the vessel diameter (D) (determined from monochromatic fundus photographs). Measurements were made in a single temporal retinal vein of each animal at baseline, during, and after each of the infusions. Plasma glucose rose from 6.1 ± 0.5-25.3 ± 1 . 5 mM (mean ± standard error) during the bolus infusion and from 6.4 ± 0.7-22.0 ± 0.7 mM during the slow infusion. The bolus and the slow glucose infusions both produced large increases in RBF (63% and 62%, respectively) which were mainly attributable to increases in V max . The urea infusion had no significant effect on RBF, V max , or D. The ocular perfusion pressure rose slowly and was significantly elevated after 60 minutes of slow glucose infusion but not after the urea infusion.